Headed anchors/studs are commonly used to connect steel members (e.g.,
columns, girders, or braces) and concrete elements (e.g., foundations,
walls, or columns, respectively). The concrete elements may experience
substantial damage (e.g., large cracking) during an earthquake; thus, a
good understanding of the behavior of anchors in cracked concrete is a
prerequisite to ensuring satisfactory seismic performance and safety of
structures. Current seismic design guidelines, represented by the
Appendix D of ACI 318-08 document, are not adequate particularly in
terms of guidelines for design of headed anchors/studs in significantly
cracked concrete. The design provisions seem to tacitly rely
on reserved capacity of anchors, and perceived ductile failure modes
due to steel fracture. Both of the rationales are questionable because
of paucity of supporting data for anchor behavior under seismic
loading. In addition, the interaction equations for anchors under
combined cyclic tension-shear have not been verified experimentally. As
a result, many anchor connections, including those taking advantage of
additional reinforcement around the anchors, are often implemented in
practice without supporting experimental data, thereby leading to
potential uncontrollable structural performance. The knowledge gap is
due partly to the limited equipment available to the community before
the NEES facilities became operational in 2004. The research team will
investigate the fundamental behavior of headed anchors/studs under
simulated seismic loading and verify and improve the anchor connection
details commonly seen in practice. As part of the proposed analytical
studies, the research team will develop connection interface models to
improve model-based simulations and to assist in the development of
performance-based engineering methodologies. Engineers, students
(including those from underrepresented groups), and general public will
be involved in the proposed research through a focused education and
outreach program. The research will advance the current seismic design
practice and enhance our ability to meet the future earthquake
challenges.